The objectives of this research proposal are to determine how easily conversational participants are able to make use of information about their co-participants' perspectives during referential communication. Three groups of experiments will be run to determine 1) the extent to which interlocutors produce and make use of gaze and body orientation information during reference to real objects, 2) the ease with which conversational participants can adapt to neutral and other-centered perspectives (ignoring their own egocentric perspective) depending on the frequency with which perspectives are shifted and the length of time with which a particular perspective is maintained, and 3) the extent to which the experience of contributing to a joint perspective in common ground affects reference interpretation in ways that contrast with interpretation in non-conversational settings. Participants will be placed in referential communication tasks, sometimes with confederate speakers. Their behavior will be monitored with (head-mounted eyetracking equipment that superimposes fixations on a scene recording and is time- locked to the recorded linguistic behavior]. The time course of reference production and interpretation will be measured by calculating the time it takes participants to look at and reach for referents. The studies will use point-of-disambiguation manipulations, varying the point in the referring expression at which an unambiguous referent is identifiable depending on whether or not information about perspective is being taken into account.